Methods of processing textile yarns



Aug; 20, 1957 N. J. STODDARD, ET AL 2,803,108

' METHODS OF PROCESSING TEXTILE YARNS Filed Jan. 4, 1954 3 Sheets-Sheet1.

INVENTORS. jvwlzalasllioadard J2.

A TTORNEYS.

Aug. 20, 1957 N. J. STODDARD ETAL 2,803,108

METHODS OF PROCESSING TEXTILE YARNS Filed Jan. 4, 1954 4 Y 5 Sheets-Sheet 2 ,7 I II I r z' 'n' EESSSSHEjgE Eiiii 50 'I INVENTORS. 47 7 I]zvz'a/wzdsczsimdfim &

A TTORNEYS.

N. J. STODDARD ET AL 2,803,108

METHODS 01 PROCESSING TEXTILE YARNS Aug. 20, 195? 3 Sheets-Sheet 3 FiledJan. 4, 1954- mvm'oas: NICHOLAS J. STODDARD B WARREN A- SEEM WWW 4 WATTYS.

United States Patent C) "ice METHODS or PROCESSING TEXTILE YARNSNicholas J. Stoddard, Berwyn, and Warren A. Seem, Chester Springs, Pa.,assignors, by mesne assignments, to Universal Winding Company, Cranston,R. 1., a corporation of Massachusetts Application January 4, 1954,Serial No. 401,803

11 Claims. (Cl. 57-157) This invention relates to thermoplastic textileyarns and methods of processing them. More particularly, it is concernedwith polyamide and other thermoplastic yarns including nylon, Vinyon,Orlon, Velon, Dacron, Saran and the like (as distinguished from yarns ofcotton, linen, rayon, silk, wool and the like), and to methods ofthermally shrinking, thermally stretching, thermally processing and/ orthermally stabilizing such synthetic yarns by thermal treatment withincidental winding, twisting, twisting and untwisting, plying, coming,copping, nubbing, drying, dyeing, coating, singeing, sizing, and othernormal processing operations, with the aforesaid thermal operationsuniformly carried out to substantially whatever degree desired orrequired and simultaneously with normal yarn processing operations.

In processing polyamides and other thermoplastic chemicals of the kindreferred to after conversion into yarns to render them suitable for usein weaving, knitting and other textile operations, it has been thecommon practise to utilize heat in many forms such as steam, hot liquidsand hot vapors to thermally shrink, thermally stretch, thermallystabilize and otherwise thermally treat the yarn, all such operationsbeing carried out before, after or between normal operation or asseparate and independent, thermal operations. For example, to set thetwist or stabilize the torsional forces after twisting, pretwistedthermoplastic yarns wound upon rigid or sometimes collapsible cores wereheretofore placed in a heated chamber. On the other hand, to shrinkthermoplastic yarns, they were subjected to heat after having been woundinto skeins, or upon collapsible cores, or loosely upon rigid cores, andagain subjected a second time to heat after rewinding. To stretchcompleted thermoplastic ply yarns or cords it has been necessaryheretofore to resort to a separate thermal stretching operation, and forimpartation of dimensional stability, to subjec the yarns to heat afterwinding upon a rigid core, and in some instances, to rewind and againheat treat the yarns.

It has also been the common practice in the past to wind thermoplasticyarns into skeins and to place the skeins into a closed heated treatingchamber for shrinking and stabilizing the yarns. Here again, when theshrinkage desired was not consistent with the heat necessary for arelatively high amount necessary for thermal stabilization, andadditional operations were therefore required in the processing. a

When thermoplastic yarns were shrunk as heretofore by subjection to heatafter being wound upon collapsible cores, or after being loosely woundupon rigid cores with a second heat treatment after re-winding, one tofour extra operations were involved in the treatment. Because of therigidity of the cores, and the varying resistance to collapsing of thepreviously wound yarn layers, uneven shrinkage or contraction of theyarns took place throughout the packages, and, as a consequence thetreated yarns varied in physical characteristics, i. e., in appearance,denier, size, dyeing properties, elongation, elasticity, strength,residual shrinkage, torsion and the like, these 7 2,833,108 PatentedAug. 20, 1957 variations and imperfections being carried through intothe fabrics ultimately made from the yarn.

In the production of fish lines, nets and the like, for example, byprior art methods, the thermal stretching was done as a separate stepafter previous processing operations, but likewise without attainment ofuniformity in the physical characteristics of the finished yarns.

In another prior art procedure for the purpose of attain ing dimensionalstability, thermoplastic yarns wound upon rigid cores were heat treated,and sometimes again rewound upon rigid cores and again heat treated.Notwithstanding these heat treatments, the processed yarns lackeduniformity in physical characteristics due to uneven shrinkage asbetween the inner and outer windings of the yarns on the cores andsubjection of the outer windings to the heat for a longer time periodthan the inner windings during each heat treatment.

Definite irregularities (such as in appearance, denier, size, dyeingproperties, yield value, contractile force, elongation, elasticity,residual shrinkage, torsion, strength, and the like) exist in packagedthermoplastic yarns as they come from the producer. These irregularitiesare due to many uncontrollable conditions during initial conversion ofthe thermoplastic chemicals into yarn strands, i. e., they areoccasioned by variations of tension in the spinning, stretching andpackaging operations, by lengthening and/ or shortening of the yarnsunder changing conditions of temperature and humidity, and by variationsin restraint upon the different layers of the yarns in the packages.Such imperfections cause, in fabrics and other products made from theyarns, corresponding irregularities which detracted from the appearanceof the products, and frequently precluded use of the yarns in certainproducts of manufacture. In other cases the heretofore conventional yarnprocessing tended to accentuate the irregularities and/ or cause morepronounced imperfections which further impair the quality of theproducts manufactured from the yarns, or additionally precluded theiruse in certain products.

Subjection of thermoplastic yarns to high temperature for prolongedperiods of time causes considerable heat degradation. For shrinkingand/or stabilization of thermoplastic yarn in packages as has been thecommon practice heretofore, the packages were exposed in a heatedchamber for an hour or more depending upon the size of the packages, thedensity of the windings and the circulation of the air in the chamber.It has been determined that the loss in tenacity of nylon yarn subjectedto a temperature of 284 F. for prolonged periods varies roughly as thelogarithm of the time exposure, and when subjected to this temperaturefor an hour the yarn loses about 4% in tenacity, in two hours it losesabout 8%, and in eight hours it loses about 24%. Accordingly, when nylonor other thermoplastic yarns are treated by the usual prior art methodsthey vary in tenacity and in other physical characteristics from theinside to the outside of the packages.

' Thus, the processing of thermoplastic yarns by these prior art methodsin preparation for weaving, knitting, or other uses entailed resort tonumerous separate treating steps as well as frequent intermediatehandlings of the yarns, all of which were painstaking, time consumingand expensive and so added very considerably to the cost of the yarns.Moreover, the results were generaly unsatisfactory from the standpointof uniformity due to the difficulty of maintaining the temperature, towhich the yarns were subjected, constant for a uniform time during thevarious separate treatments.

The chief aim of our invention is to overcome the herein pointed outdrawbacks in the prior methods of processing thermoplastic yarns inpreparation for use in the manufacture of woven, knitted and othertextile prodnets, and to make possible the economic production ofthermoplastic yarns which are uniform throughout as regards theirphysical characteristics. This objective is realized in practice, ashereinafter more fully disclosed, through provision of a simple andreliable method whereby improved uniformly processed thermoplastic yarnsare produced in quantity in a rapid continuous manner at greatly reducedcost. Our method of processing provides the presence of heat andcorrelated yarn tension which we have discovered to be even moreimportant for the best processing of thermoplastic yarn than theestablished practice of regulating relative humidity during theprocessing of other than thermoplastic yarns. This is broadlyaccomplished by introducing in the path of travel of the yarn duringwinding, twisting, twisting and untwisting, plying, coning, copping,nubbing, drying, dyeing, coating, singeing, sizing or the like, athermally insulated regulatable restricted heated zone together with aregulatable yarn tension device; and then uniformly heating thetraveling yarn under correlated tension.

Other objects and attendant advantages will appear from the followingdetailed description when considered in connection with the attacheddrawings, wherein:

Fig. 1 is a fragmentary view, in front elevation, of an exemplaryapparatus suitable for processing thermoplastic yarns in accordance withour improved method.

Fig. 2 is a fragmentary view in vertical section, taken as indicated bythe angled arrows II-li in Fig. 1 and drawn to a larger scale, showingone type of a specially designed heating device embodied in theapparatus.

Fig. 3 is a detail sectional view taken as indicated by the angledarrows lIilII in Fig. 2, and showing one type of a specially designeddevice by which the yarns are maintained under tension during theprocessing.

Fig. 4 is a view like Fig. 3, showing another form of a speciallydesigned tensioning device.

Fig. 5 is a fragmentary view in front elevation of a modified form ofthe apparatus which is suitable for dyeing and chemically sizingthermoplastic yarns; and

Fig. 6 is a side elevational view of the apparatus disclosed in Fig. 5.

It is to be pointed out that we do not limit our process to the twotypes of tension devices shown in Fig. 3 and Fig. 4 since it is obviousthat many variations in design are possible without departing from theinvention. The basic requirement for a tensioning device to be utilizedin our process is that it be capable of applying the re quired yarntension uniformly.

The apparatus illustrated in Fig. 1 is basically what is ordinarilyknown in the textile art as an up-twister such as is commonly used intwisting operations, one of the usual multiple spindles for a woundpackage P of unprocessed yarn being indicated at 2, the traverse railfor the corresponding distributing guide 3 being indicated at 4, a usualdrive roll for the collecting spool S being indicated at 6, and therotary shaft of said roll being indicated at 7. Spindle 2 is rotated bytangential contact of its diametrically enlarged lower portion 8 with arunning belt 9.

In converting the apparatus for the purposes of our invention, wearrange in the interval between the spindle 2 and the traverse guide 3,a heating device 10, and a yarn tensioning means 11 along the line ofupward travel of the thermoplastic yarn Y, i. e., upwardly from thesupply package P to the collecting spool S. As presently explained, thedevice 19 is electrically heated, current being conducted to it throughtwo fixed horizontal bus bars 12 and 13 whereto said device is secured,with interposition of insulation bushings at 14, by screws 15 and 16 asbest shown in Fig. 2. The required degree of heat is uniformlymaintained in the device 10 by current at a constant voltage (notexceeding twenty-four volts for personal safety) through an automaticinduction voltage regulator 17 from a power line 18, 19, said regulatorbeing connected by conductors Zti, 21 to a manually adjustable 4.induction voltage regulator 22 connected in turn by conductors 23, 24 tothe primary of a step down transformer 25 in circuit through conductors26, 27 with the bus bars 12, 13. The output voltage of the inductionvoltage regulator 17 is automatically governed by a thermally responsivesensing means 23 incorporated in the heating device 1%. The automaticand the manual voltage regulators 17 and 22 and the thermostatic sensingmeans 28 may all be of any approved standard and commercially availabletypes by cooperation of which the temperature in the heating device 10is modulated compensatively with changes in ambient or room temperatureand transfer of heat to the travelling yarn. Also included in the lines18, 19 and 2t 21 respectively, are suitable manually operable safetyhand switches 29 and 31).

As shown in Fig. 2, the heating device It comprises a central tube 32,of non-ferrous material and of small diameter and bore, through whichthe yarn Y is passed, said tube being exteriorly coated as at 33 withglass or other electrical insulation, and surrounded bya coil 34 ofresistance wire. As further shown, tube 32 is embedded in a thick walledjacket 35 of thermal insulation which may be of fiber glass Sil-O-Celgranules or the like encased in a metallic shell 36. At its oppositeends, the shell 36 is closed by covers 37 which also may be of metal,with interposition between them and the heat insulating jacket material35, of disks 38 of transite or the like to minimize thermal transferfrom the hot tube 32 to said shell and vice versa. Engaged over theopposite ends of tube 32 and passing through the disks 38 are hardwear-resistant bushings 39 which may be of porcelain or the like, toprevent cutting of the tube by the yarn passing through it. It is to beparticularly noted that the winding pitch of the heating coil 34increases progressively from the bottom end of the tube 32 at which theyarn enters, to the mid height of the tube, and that it progressivelydecreases toward the end at which the yarn emerges. As a result, agreater amount of electric energy is available at the entrant and at theexit ends of tube 32, thereby making possible the maintenance of thedesired uniform elevated temperature throughout the tube and the use ofa much shorter tube than otherwise would be required. The lead it fromone end of coil 34 is extended through the cover 37 to the screws 15,and the lead 41 from the other end of said coil to the screw 16.interposed in lead is a hand switch which is diagrammatically indicatedat 42.

We do not limit our process to the use of the one design of heatingdevice shown as 10 in Fig. 2 since it is obvious that many variations indesign are possible without departing from the invention. The heatingdevice shown as 10 in Fig. 2 is very practical for our process since itis capable of supplying uniform (11%) heat up to the melting point ofthe yarn without materially afiecting room temperature.

The tensioning or restraining means 11 comprises, in this instance, asmall V grooved Wheel 45 about which one or more turns of the yarn Y arewrapped, said wheel being revolvable about the laterally bent end of asupporting shank member 46, and is engaged by a friction disk 47 whichis backed by a compression spring 48, the force of the latter beingfinely regulatable by means of a thumb nut 49. As best shown in Figs. 2and 3, the shank member 46 extends through a vertical slot 50 in abracket bar 51 of metal suspended from bus bar 13, and is fixable afteradjustment up or down and in and out by means of the clamp nutsindicated at 52. Arranged below the tensioning means 11 and similarlysupported by the bracket bar 51 with capacity for both up and down andin and out adjustment is a pigtail guide 53 for the yarn Y, said guidebeing fixable in adjusted position by clamp nuts 54. 7

Again referring to Fig. 1, it will be noted that the thermoplastic yarnY from the supply package 1 is threaded upwardly through one eye of theflyer 55 associated with spindle 2, then through the stationary guide53, then one or more times about the wheel 45 of the tensioning means11, then through the tube 32 of heating device 10, and finally throughthe traverse guide 3 enroute to the collecting spool S.

In the operation of the apparatus to carry out our improved processingmethod, the yarn Y is drawn upward at a uniform linear speed from thesupply package P on spindle 2 by the pull of the rotating take-up spoolS, being maintained all the while under a' predetermined constanttension by the tensioning device 11 in the interval between the latterand said take-up spool as it traverses the heating device 10. In theinterval between the revolving supply package P and the wheel 45, theyarn is twisted by rotation of said package. As the yarn traverses theheating device immediately after being twisted, it is softened orplasticized, and by cooling, after emergence from said device on its wayto take-up spool S, it is thermally stabilized and the twist, previouslyinserted, is set. By this it is meant that the yarn is yarn-set, thatis, the molecules in the thermoplastic yarn are permanently anduniformly reoriented or realigned therein according to the physicalconfiguration of the yarn at the time of yarn-setting so that theindividual filaments of the yarn have an inherent tendency to retain orassume the physical configuration which they had at the time ofyarn-setting. By adjusting the thumb nut 49 the resistance to freerotation of the wheel 45 can be varied to keep the tension at less thanthe contractile force of the yarn to shrink and stabilize the yarn, tomaintain the tension equal to the contractile force of the yarn whenstabilization only is desired, or to increase the tension beyond thecontractile force of the yarn to stretch and stabilize it.

During the processing, the temperature in the heating device 10 ismaintained at a definite prescribed degree, depending upon theadjustment of the manual induction voltage regulator 22, and modulatedcompensatively with changes in ambient or room temperature and transferof heat to the travelling yarn through influence of the thermostaticsensing means 28 in said heating device upon the automatic inductionvoltage regulator 17. By reason of the thick thermal insulationsurrounding the coil 34 of the heating device 10, a very little thermaltransfer actually can take place between the yarn tube 32 and theoutside atmosphere. As a consequence, the required degree of yarntreating temperature is uniformly maintained in the restricted zonedefined by the heating device. By adjusting the tensioning device 11,the tension to which the yarn is subjected can be accurately correlatedwith the effective treating temperature and the constant linear speed oftravel of the yarn under the pull of the rotating take-up spool S. It isto be understood that the temperature will be adjusted in accordancewith the requirements of the particular kind of thermoplastic yarn whichis to be processed, and the tension adjusted in accordance with thecharacteristics desired in the finished yarn.

The effect of heat upon the different thermoplastic yarns now incommercial use is generally known and can be readily determined for newthermoplastic yarns. For each particular thermoplastic yarn varioustemperatures have a definite effect upon shrinkage, stabilization,tenacity, yield under stress, contractile force, elasticity, breakingelongation and other physical characteristics. By correlation of auniform prescribed heat and imposition of very little tension, inaccordance with our invention, maximum shrinkage will be permitted totake place uniformly throughout the length of the yarn. By applyingtension just equal in degree to the contractile force of the yarn at thegiven temperature, neither shrinkage or stretching will take place;while by applying high tension, maximum stretching will take placethroughout the length of the yarn. Thermoplastic yarn treated inaccordance with our new method takes dyes evenly, and greater permanencyand depth of color result from the uniform heating at 6 the elevatedtemperatures with increase in tenacity and in the modulus of elasticityof certain types of thermoplastic yarns.

In carrying out our improved processing method it is essential, asalready been pointed out, that the speed of linear travel of the yarnthrough the restricted heating zone 10 must bear a definite relation tothe extent of heat transfer to the running yarn. We have found it to bea simple matter to predetermine the extent of thermal transfor in therestricted heating zone to a particular yarn at any given temperatureand any given speed of travel. For example, with a temperature of 485 F.maintained in the heating zone, 200 denier nylon yarn run through saidzone at the rate of 600 inches per minute Will shrink 8%. Since it isknown that a dry temperature of 400 F. is required to shrink 200 deniernylon by the same amount, it is evident that the effective temperaturein the heating device for that particular yarn and linear speed oftravel must be 400 F. It is to be understood that by effectivetemperature we do not necessarily mean the temperature in the heatingzone, but rather to the temperature required to obtain a given effect onthe particular thermoplastic yarn involved if said yarn were nottravelling but mearely heated to that temperature. Thus, by our improvedmethod, it is possible to predetermine thermal shrinking, thermalstretching, thermal processing and/or thermal stabilization to anydesired extent within the limits of the characteristics of theparticular yarns, with or without incidental twisting as may be desiredby regulation of the yarn tension and the temperature of the restrictedheated zone. With many types of thermoplastic yarns, the presence ofmoisture adds substantially to the eflectiveness of the heat at a giventemperature in the processing. To those familiar with the art, it willbe evident that it is a simple matter to adequately wet out the runningyarn with water or other liquid solution of effective chemicals prior topassage of the yarn through the restricted heating zone.

In our improved method of processing, it is no longer necessary toaccept as unavoidable and to make the best of many of the undesirableand thermal characteristics of processed thermoplastic yarns. Rather,our improved method makes it possible to economically processthermoplastic yarns with utilization of the maximum thermal qualitiesand improvement of their physical properties.

A few examples are given below of the procedures followed according toour invention in the processing of thermoplastic yarns for differentpurposes and uses.

To prepare nylon yarn for use in the welts of ladies stockings, themanual voltage'regulator is adjusted to provide an effective temperaturein the heating device 10 of'250 F. more or less depending upon thetemperature used in subsequently preboarding of the hosiery in the usualway, adjusting the tensioning device, and running the yarn in theapparatus after the manner previously described, whereby the yarn istwisted, uniformly shrunk, stretched and/ or stabilized to the degreedesired. Thermoplastic yarn so-processed will lend itself to be formedinto uniform stitches by the needles of the knitting machines because itis set and molded to substantially smooth or rod shaped form. If, in theprocessing, the running nylon yarn is subjected to an effectivetemperature of 350 F. in the heating device, a tension of less than 0.4gram per denier will cause the yarn to shrink while being twisted andthermally stabilized. Maintenance of a tension of more than 0.4 gram perdenier, with other conditions remaining the same, will result instretching of the yarn as it is twisted and stabilized; while under atension of approximately 0.4 gram per denier, the yarn will simply bestabilized as it is twisted, without either shrinking or stretching.This continuous procedure is thus simple as compared with the prior artslow methods of thermoplastic hosiery welt yarn processing. whichinvolved the separate stages of redrawing the nylon yarnfrom' theshipping bobbin or 7 pirn; uptwisting the yarn; reeling the yarn into askein; shrinking the skein yarn while relaxed on a pole or wrapped in abundle; backwinding the yarn; and finally coning the yarn.

To produce 30 turn 30 denier nylon leg yarn for ladies hosiery inaccordance with our method, the twist setting or thermal stabilizing isaccomplished simultaneously with uptwisting. In the usual prior artmethod of processing such yarn, the yarn was first twisted and spooled,and the spool placed for 90 minutes in a chamber wherein the atmospherewas heated to a dry bulb temperature of 170 F. and a wet bulbtemperature of 160 F. to set the twist or thermally stabilize the yarnto prevent kinking or snarling in the knitting. Aside from being muchmore rapid, it will be seen that we have eliminated the double handlingrequired by the prior art methods of preparing nylon leg yarn for ladieshosiery, the improved finished yarn being uniform in its physicalcharacteristics and favoring the production of hosiery of improvedattractive appearance, tit and length by reason of the uniformity of itsstitches and residual shrinkage.

Another type of new and useful thermoplastic yarn can be produced inaccordance with our invention by doubling and twisting two ends at lowtension on a double-twister equipped with a heating unit constructed ashereinbefore described with an effective temperature of 400 F.maintained therein, one of the ends having had no previous thermalprocessing but the other end having previously been redrawn undertension through a similar heating unit installed in a conventionalredraw machine also at 400 F. effective temperature. As a result of thisprocessing, the end not previously thermally twisted, hrinkssubstantially and is wrapped by the other end which did not shrink, thefinished yarn thus taking on a desirable cork screw appearance.

To produce a 100 denier 70 turn per inch nylon yarn having a sandysurface and substantially devoid of residual shrinkage, in accordancewith our invention, we uptwist the yarn 70 turns per inch at 12,000 R.P. M. utilizing no flier and relying upon the ballooning, which takesplace as the yarn is ravelled from the supply, to impart a low tensionof approximately 7 grams. It will be seen that the sandy appearance ofthe yarn results as a consequence of this high twisting of the unheatedyarn at the low tension. Yarn so twisted is then run in the apparatus ofFig. 1 with an effective temperature of 400 F. maintained in therestricted heating zone and thereby thermally shrunk, with attendantaccentuation of the sandy appearance.

To produce 100 denier 70 turn per inch nylon yarn having a smoothsurface and a dull appearance with substantially no residual shrinkage,the procedure followed is the same as in the example immediately aboveexcept for the substitution in the apparatus of Fig. 1 of the modifiedtensioning means 11a shown in Fig. 4. In this modified tensioning means,instead of a grooved wheel, a pair of opposing friction disk 45a aremounted for free rotation upon the laterally bent end of the shankmember 46a. The yarn is passed between the disks 4511, one of the latterbeing yieldingly pressed toward the other by a spring 48a which isfinely regulatable by a thumb screw 49a threadedly engaged upon thedistal end of the shank member 46a. For the instant purpose, the spring48a is adjusted to apply a tension of 80 grams upon the yarn as thelatter passes between the disks 46a, this degree of tension beinggreater than the contractile force of the yarn while it is heated to theelevated temperature and is being twisted. This twisting and stretchingcauses the heated yarn to assume the desired smooth appearance and tohave substantially no residual shrinkage.

To produce a 140 denier plied Dacron yarn, having a minimum ofresidualshrinkage and elongation as well as uniformity of other physicalcharacteristics, in which two ends of 70 denier are each 5 twisted .24turns 'per inch and Z twisted together 20 turns per inch, we firstup-twist the respective ends in the apparatus of Fig. l with maintenanceof an effective temperature of 350 F. in the heating device 10 andapplication of a tension of 70 grams to substantially stretch said endsand thermally stabilize their torsional forces. With this accomplished,we ply the two ends on a down spinner equipped with a similar heatingdevice maintained at an effective temperature of 380 F. under a tensionof grams to further stretch and stabilize the torsional forces, andfinally up-twist the yarn 20 turns Z in the apparatus of Fig. 1 at atemperature of 400 F. at a tension of grams to still further stretch andthoroughly stabilize the yarn'dimensionally and torsionally. While agenerally similar yarn could be produced by utilizing certain proceduresknown in the prior art, a great many more separate steps andintermediate handlings would have to be resorted to, but such yarn wouldlack uniformity in physical characteristics for the reasons previouslypointed out.

To prepare thermoplastc yarns, suitable for tricot knitting, inaccordance with our invention, We first wind the yarn from the producersdelivery packages upon cones at an effective elevated temperature andunder a tension consistent with optimum shrinkage and tenacity, byrunning them in a cone winder equipped with a heating device and aregulatable tensioning device like those described in connection withFig. 1. In this example, only one normal operation is required. If thesame requirements were to be met by prior art conventional methods, atleast two additional costly operations would be involved namely, windingthe yarn into a skein, and shrinking it while in the skein.

To produce uniformly dyed thermoplastic yarn, having maximum tenacityand a minimum of elongation on cones for use in circular knittingmachines, the apparatus of Figs. 5 and 6 is utilized on which we conewind the yarn from the producers package 201 in one operation by firstpassing it through a trough 202 containing a dye solution before runningit through the yarn tension 203 and the heating device 204 and thenwinding it onto the constant thread speed cone take-up c, with theeffective temperature and the tension so correlated as to obtain maximumstretch without loss of tenacity. In this example, the yarn Y is driedand the dye developed by the action of the effective elecatedtemperature during traverse of the yarn through the restricted heatingzone. Production of such dyed yarns heretofore, required two separateoperations to wit: thermal stretching of the yarn, and drying the yarnand developing the dye. Aside from being more costly than yarns producedaccording to our new method, the processed prior art dyed thermoplasticyarns lacked the desired uniform physical characteristics.

To produce a chemically sized highly twisted uniform nylon yarn withtorisonal forces stabilized, in accordance with our new method, we runthe yarn from a package 201a of highly twisted nylon yarn in a sizingmachine as in Figs. 5 and 6 having a constant thread speed cone take-upc and heating and tensioning means like those in Figs. 5 and 6,utilizing an efitective temperature of 250 F. for stabilization, and atension of 30 grams. The prior art production of yarns of this typeentailed a separate stabilizing operation, and the desired uniformity asto characteristics could not be obtained due to irregular shrinkmg.

To produce a yarn of maximum strength in which an end of thermoplasticyarn is doubled or plied with an end of cotton, in accordance with ourinvention, we thermally stretch the thermoplastic end to obtain the sameelongation at the breaking point as the cotton end runs the two endstogether in the apparatus of Fig. 1, the thermal stretching being thusaccomplished simultaneously with the plying. conventionally, severaladditional 9 operations would be required for attainment ofcorresponding results.

To produce substantially permanently set highly twisted thermoplasticyarn which is to be untwis-ted so as to become crimped, waved orflulfed, in accordance with our invention, we run the yarn continuouslyin a conventional up-twister equipped like the apparatus of Fig. l witha tensioning means and a heating device and subject the yarn to a higheffective temperature and high tension whereby the thermal setting orstabilizing is accomplished simultaneously with the twisting.

To continuously produce permanently set highly twisted crimped, wavy orfluifed yarn in one continuous operation, according to our invention, werun the yarn in an up-twister equipped like the apparatus of Fig. l witha yarn tensioning means and a heating device, but with a specialtwisting and untwisting spindle such that the yarn is twisted whileheated and then cooled, and the untwisting accomplished withoutinterruption in the travel of the yarn. Such processing cannot be done,as far as we are aware, by any prior art method.

To process 70 denier nylon yarn, as received on a pirn from themanufacturer, for attainment of uniformity in appearance, denier size,dyeing properties, elongation, elasticity, residual shrinkage, etc., inaccordance with our invention we unwind the yarn from the pirn insteadof from a rotated package in the apparatus in Fig. l, and run it throughthe apparatus in the same manner as previously described withmaintenance of a uniform effective temperature of 385 F. and a uniformtension between and 140 grams.

It is understood that the heating and tensioning devices herein shownare to be considered as exemplary of others which could be usedproviding that they are capable of maintaining the uniform temperaturesand tensions necessary for attainment of the physical characteristics ofour improved thermoplastic yarns.

From the foregoing it will be seen that we have provided a simple methodby which various kinds of improved thermoplastic yarns for dilferentpurposes can be thermally processed more rapidly and at a much lowercost than heretofore, with assurance of uniformity in appearance andother desired physical characteristics.

The illustrated apparatus, per se, forms the subject matter of a.separate patent application, Serial No. 401,952 concurrently filedherewith.

Having thus described our invention we claim:

1. A method of thermally processing thermoplastic yarn which comprisescontinually drawing the yarn from a source of supply, continuallypassing the yarn at a selected linear speed under uniform tensionthrough a restricted thermally isolated and uniformly heated zone touniformly heat the yarn to a prescribed temperature to yarn-set thesame, controlling the supply of heat energy to said zone to therebymaintain said heated zone uniformly at the temperature required touniformly heat said yarn to said prescribed temperature, continuallycooling the yarn to stabilize the same after passage under tensionthrough said heated zone, winding the processed yarn, and correlatingthe tension in said yarn to said prescribed temperature and linear speedof travel of the yarn to maintain the yarn at a uniform tension relativeto the contractile force and thermal characteristics of the yarnresulting from heating the same.

2. A method of thermally processing thermoplastic yarn which comprisescontinually drawing the yarn from a source of supply, continuallypassing the'yarn at a selected linear speed through a restrictedthermally isolated and uniformly heated zone to uniformly heat the yarnto a prescribed temperature to yarn-set the same, controlling the supplyof heat energy to said zone compensatively according to the ambienttemperature and rate of transfer of heat to the yarn to thereby maintainsaid heated zone uniformly at the temperature required to uniformly heatsaid yarn to said prescribed temperature, continually cooling the yarnto stabilize the same after passageunder tension through said heatedzone, winding the processed yarn, maintaining the yarn under a uniformtension during heating, cooling and winding thereof, and correlating thetension in said yarn to said prescribed temperature and linear speed oftravel of the yarn to maintain the yarn at a selected uniform tensionrelative to the contractile force and thermal characteristics of theyarn resulting from heating thereof.

3. A method of thermally processing thermoplastic yarn which comprisescontinually drawing the yarn from a source of supply, continuallypassing the yarn at a selected linear speed through a restrictedthermally isolated and uniformly heated zone to uniformly heat the yarnto a prescribed temperature to yarn-set the same, controlling the supplyof heat energy to said zone com.- pensatively according to the ambienttemperature and rate of transfer of heat to the yarn to thereby maintainsaid heated zone uniformly at the temperature required to uniformly heatsaid yarn to said prescribed temperature, continually cooling the yarnto stabilize the same after passage under tension through said heatedzone, winding the processed yarn, maintaining the yarn under a uniformtension during heating, cooling and winding thereof, and correlating thetension in said yarn to said prescribed temperature and linear speed oftravel of the yarn to maintain the yarn at a uniform tension less thanthe contractile force of the yarn resulting from heating the same toshrink the yarn.

4. A method of thermally processing thermoplastic yarn which comprisescontinually drawing the yarn from a source of supply, continuallypassing the yarn at a selected linear speed through a restrictedthermally isolated and uniformly heated zone to uniformly heat the yarnto a prescribed temperature to yarn-set the same, controlling the supplyof heat energy to said zone compensatively according to the ambienttemperature and rate of transfer of heat to the yarn to thereby maintainsaid heated zone uniformly at the temperature required to uniformly heatsaid yarn to said prescribed temperature, continually cooling the yarnto stabilize the same after passage under tension through said heatedzone, winding the processed yarn, maintaining the yarn under a uniformtension during heating, cooling and winding thereof, and correlating thetension in said yarn to said prescribed temperature and linear speed oftravel of the yarn to maintain the yarn at a uniform tension equal tothe contractile force of the yarn to stabilize the same.

5. A method of thermally processing thermoplastic yarn which comprisescontinually drawing the yarn from a source of supply, continuallypassing the yarn at a selected linear speed through a restrictedthermally isolated and uniformly heated zone to uniformly heat the yarnto a prescribed temperature to yarn-set the same, controlling the supplyof heat energy to said zone compensatively according to the ambienttemperature and rate of transfer of heat to the yarn to thereby maintainsaid heated zone uniformly at the temperature required to uniformly heatsaid yarn to said prescribed temperature, continually cooling the yarnto stabilize the same after passage under tension through said heatedzone, winding the processed yarn, maintaining the yarn under a uniformtension during heating, cooling and winding thereof, and correlating thetension in said yarn to said prescribed temperature and linear speed oftravel of the yarn to maintain the yarn at a uniform tension greaterthan the contractile force of the yarn to stretch and stabilize thesame.

6. A method of thermally processing thermoplastic yarn which comprisescontinually drawing the yarn from a source of supply, continuallytwisting the yarn, continually passing the yarn at a selected linearspeed under uniform tension through a restricted thermally isolated anduniformly heated zone to uniformly heat the yarn to a prescribedtemperature to reorient the molecules asoatos of the yarn to the'twisted formation ofthe yarnand yarn-set thesame, controlling thesupplyof heat energy to said zone compensatively according to theambient temperature and rate of transfer of heat to the yarn to therebymaintain said heated zone uniformly at the temperature required touniformly heat said yarn to said prescribed temperature, continuallycooling the yarn to stabilize the same after passage under tensionthrough said heated zone, winding the processed yarn, and correlatingthe tension in said yarn to said prescribed temperature and linear speedof travel of the yarn to maintain the yarn at a uniform tension relativeto the contractile force and thermal characteristics of the yarnresulting from heating and twisting the same.

7. A method of thermally processing thermoplastic yarn which comprisescontinually drawing the yarn from a source of supply, continuallytwisting the yarn, continually passing the twisted yarn at a selectedlinear speed through a restricted thermally isolated and uniformlyheated zone to uniformly heat the yarn to a prescribed temperature toreorient the molecules of the yarn to the twisted formation of the yarnand yarn-set the same, controlling the supply of heat energy to saidzone compensatively according to the ambient temperature and rate oftransfer of heat to the yarn to thereby maintain said heated zoneuniformly at the temperature required to uniformly heat said yarn tosaid prescribed temperature, continually cooling the twisted yarn tostabilize the same after passage under tension through said heated zone,winding the processed yarn, maintaining the twisted yarn under a uniformtension during heating, cooling and winding thereof, and correlating thetension in said yarn to said prescribed temperature and linear speed oftravel of the yarn to maintain the yarn at a selected uniform tensionrelative to the contractile force and thermal characteristics of theyarn resulting from heating and twisting the same.

8. A method of thermally processing thermoplastic yarn which comprisescontinually drawing the yarn from a source of supply, continuallytwisting the yarn, continually passing the twisted yarn at a selectedlinear speed through a restricted thermally isolated and uniformlyheated zone to uniformly heat the yarn to a prescribed temperature toreorient the molecules of the yarn to the twisted formation of the yarnand yarn-set the same, controlling the supply of heat energy to saidzone compensatively according to the ambient temperature and rate oftransfer of heat to the yarn to thereby maintain said heated zoneuniformly at the temperature required to uniformly heat said yarn tosaid prescribed temperature, continually cooling the twisted yarn tostabilize the same after passage under tension through said heated zone,winding the processed yarn, maintaining the twisted yarn under a uniformtension during heating, cooling and winding thereof, and correlating thetension in said yarn to said prescribed temperature and linear speed oftravel of the yarn to maintain the yarn at a uniform tension less thanthe contractile force of the yarn resulting from heating and twistingthe same to shrink the same.

9. A method of thermally processing thermoplastic yarn which comprisescontinually drawing the yarn from a source of supply, continuallytwisting the yarn, continually passing the twisted yarn at a selectedlinear speed through a restricted thermally isolated and uniformlyheated zone to uniformly heat the yarn to a prescribed temperature toreorient the molecules of the yarn to the twisted formation of the yarnand yarn-set the same, controlling the supply of heat energy to saidzone compensatively according to the ambient temperature and rate oftransfer of heat to the yarn to thereby maintain said heated zoneuniformly at the temperature required to uniformly heat said yarn tosaid prescribed temperature, continually cooling the twisted yarn tostabilize the same after passage under tension through said heated zone,winding the processed yarn, maintaining the twisted yarn under a uniformtension during heating, cooling and winding thereof, and correlating thetension in said yarn to said prescribed temperature and linear speed oftravel of the yarn to maintain the twisted yarn at a uniform tensionequal to the contractile force of the yarn to stabilize the same.

10. A method of thermally processing thermoplastic yarn which comprisescontinually drawing the yarn from a source of supply, continuallytwisting the yarn, continually passing the twisted yarn at a selectedlinear speed through a restricted thermally isolated and uniformlyheated zone to uniformly heat the yarn to a prescribed temperature toreorient the molecules of the yarn to the twisted formation of the yarnand yarn-set the same, controlling the supply of heat energy to saidzone compensatively according to the ambient temperature and rate oftransfer of heat to the yarn to thereby maintain said heated zoneuniformly at the temperature required to uniformly heat said yarn tosaid prescribed temperature, continually cooling the twisted yarn tostabilize the same after passage under tension through said heated zone,winding the processed yarn, maintaining the twisted yarn under a uniformtension during heating, cooling and winding thereof, and correlating thetension in said yarn to said prescribed temperature and liner speed oftravel of the yarn to maintain the twisted yarn at a uniform tensiongreater than the contractile force of the yarn to stretch and stabilizethe same.

11. A method of thermally processing and dyeing thermoplastic yarn whichcomprises continually drawing the yarn from a source of supply,continually applying a dye to the yarn travelling at a selected linearspeed, continually passing the yarn at a selected linear speed underuniform tension through a thermally isolated and uniformly heated zoneto uniformly heat the yarn to a prescribed temperature to dry anduniformly develope the dye-stuif and yarn-set the yarn, controlling thesupply of heat energy to said zone compensatively according to theambient temperature and rate of transfer of heat to the yarn to therebymaintain said heated zone uniformly at the temperature required touniformly heat said yarn to said prescribed temperature, continuallycooling the yarn to stabilize the same after passage under tensionthrough said heated zone, winding the processed yarn, and correlatingthe tension in said yarn to said prescribed temperature and linear speedof travel of the yarn to maintain the yarn at a uniform tension relativeto the contractile force and thermal characteristics of the yarnresulting from heating the same and relative to the chemicalphysicalproperties of the dyestufi.

References Cited in the file of this patent UNITED STATES PATENTS

2. A METHOD OF THERMALLY PROCESSING THERMOPLASTIC YARN WHICH COMPRISESCONTINUALLY DRAWING THE YARN FROM A SOURCE OF SUPPLY, CONTINUALLYPASSING THE YARN AT A SELECTED LINEAR SPEED THROUGH A RESTRICTEDTHERMALLY ISOLATED AND UNIFORMLY HEATED ZONE TO UNIFORMLY HEAT THE YARNTO A PRESCRIBED TEMPERATURE TO YARN-SET THE SAME, CONTROLLING THE SUPPLYOF HEAT ENERGY TO SAID ZONE COMPENSATIVELY ACCORDING TO THE AMBIENTTEMPERATURE AND ATE OF TRANSFER OF HEAT TO THE YARN TO THEREBY MAINTAINSAID HEATED ZONE UNIFORMLY AT THE TEMPERATURE REQUIRED TO UNIFORMLY HEATSAID YARN TO SAID PRESCRIBED TEMPERATURE, CONTINUALLY COOLING THE YARNTO STABILIZE THE SAME AFTER PASSAGE UNDER TENSION THROUGH SAID HEATEDZONE, WINDING THE PROCESSED YARN, MAINTAINING THE YARN UNDER A UNIFORMTENSION DURING HEATING, COOLING AND WINDING THEREOF, AND CORRELATING THETENSION IN SAID YARN TO SAID PRESCRIBED TEMPERATURE